Is it possible for A to observe C influencing B, if A is outside the sphere of influence of C?
For example, can we observe the gravitational force acted upon something in our observable universe, if one of the objects exerting the force is outside our observable universe?
Other urls found in this thread:
en.wikipedia.org
en.wikipedia.org
twitter.com
Is gravity constant in both A and C?
What do you mean? There is no gravity exerted on A in this example.
This is actually what made me ask the question, and it doesn't seem to answer it. Because I heard that dark flow is constant velocity, in other words not subject to gravity right now. But my question is why not, can't the outer part of our universe still be accelerated by whatever causes dark flow, if it's still within that object's observable universe?
"Observable" means "can be interacted with"
Anything that C can interact with that A also can interact with is null (thus either A or C) or is equal to A, C and the union of both.
That is to say, any point subject to the same force from two points means that the two points must interact with each other, A and C are in the same "observable universe" so to speak
>constant velocity
As if we have the ability to measure the speed of something most of the universe away accurately enough to say whether or not it's accelerating. We can barely tell what direction shit is moving.
wouldnt that mean that we could chain out causality to an infinite length?
"Can be interacted with" doesn't imply "will interact" or "always interacts"
There are particles that simply do not interact with most other particles, but you can't say they are in another field or another universe, because they do interact with other particles, that in their own also interact normally with others, and so on
"Causality" or really just the transfer of information, cannot go faster than the speed of light. So even if something outside the observable universe effects something inside it, you won't be able to observe that effect until it's inside the observable universe. Remember that what we see as the borders of the observable universe is actually the events of billions of years ago.
That's how we found Neptune, so yes.
I don't think Neptune was ever outside our observable universe.
You don't understand what said. He is referencing that we simply did not have strong enough telescopes to look at Neptune because it was so far from Earth. But, we could see that Uranus was in a weird orbit, and the weird orbit was caused by Neptune's gravitational pull.
Even back then our "observable universe" still extended beyond the orbit of Neptune.
We could still see the stars.
Regardless, our observable universe wouldn't be the same as the observable universe from the perspective of object b, gravitational waves and photons go at the same speed, so the gravitational pull of C could affect B before any information from C reaches us at A. Neptune was just an instance or something similar to the given situation happening.
And we could observe that gravitational effect without ever seeing object C
For A to observe B influencing C, the influence would have to first travel from C to B, then from B to A, making C within A's observable universe, so no, A cannot observe B influencing C in your model. Gravity must respect the speed of light, (I think).
I won't even be in college until December though, so I'm just talking out of my ass.
I think you're confused by the question. You need to elaborate more on your ideas.
If A can fully account for movement of things in A's observable universe than it will notice that C is moving in ways that can't be accounted for by A's physical model of the universe. This means in effect that C is actually part of As observable universe, however we know it isn't. To me this seems to be an issue and I can't quite figure out the whole story
I just ran a simulation of this in Universe Simulator 2. The force of A and C tear apart mass B in the center. So, yeah you could observe the gravitational affect if you can prevent B from being annihilated, but in a practical example of where this phenomena would be observed in the real world, mass B would only technically be unobservable because it would be destroyed.
>You cannot observe something that cannot exist.
I think you completely missed the question.
How can A notice C while C is outside of it's observable universe?
>s it possible for A to observe C influencing B, if A is outside the sphere of influence of C?
depends what you mean by "Sphere of influence"
If you mean that C is completely undetectable in any way (i.e. unable to influence A visually, gravitationally, or by ANY physical means) then no, we would assume B moves that way on its own
we could only posit the existence of C, we can't "observe" it influencing B
because it cannot explain the movements of B. There must be an outside force. dunnow much a cound aldcutly lern tho
space is the final frontier but it's made in a Hollywood basement. That we're paying for. Check the Bible
This is right. C can affect B but A has to wait for the effect to cover the BA distance to observe it so by the time the effect is observed C would be in the observable universe.
>if one of the objects exerting the force is outside our observable universe?
With the expansion of the universe it's possible that A could observe the effects of past C on B but won't ever be able to observe present or future C effects. That's what dark flow is supposed to be.